The present technology relates to an imaging device, an imaging apparatus, a production apparatus and method, and a semiconductor device. Specifically, the present technology relates to an imaging device, an imaging apparatus, a production apparatus and method, and a semiconductor device that are capable of appropriately and easily controlling a level of a dark signal.
In the past, there may have been caused an Optical Black (OPB) level difference which is a difference between a dark signal in an effective pixel and a dark signal in an Optical Black (OPB) pixel in an imaging device. In addition, even within an effective pixel region, the dark signal tends to vary pixel to pixel. For example, in a peripheral region of the effective pixel (a frame-shaped region), dark signal shading where the dark signal is gradually increased may be caused.
As a method of controlling or correcting such a dark signal, the following various methods have been considered.
For example, in order to control a dark signal, there has been a method of controlling the dark signal by adjusting conversion efficiencies through adjustment of a gate area of an amplifier transistor (see JP 3326940B, for example). This method may raise a concern of reduction of mutual conductance (gm) due to an increased gate area or occurrence of short channeling due to a reduced gate area, which lead to gain variability.
In addition, there is also a method of adjusting conversion efficiencies through adjustment of a wiring pattern or a diffusion layer, thereby to control the dark signal (see JP 2006-165006A, for example). However, there is a concern that changes of conversion efficiencies may lead to variations of image capturing characteristics at the time of a bright state, which may result in degraded image quality at the time of a bright state.
Moreover, there is also a method of changing sensor potentials, thereby to control the dark signal (see JP 2012-23319A, for example). In this method, a readout voltage, a saturation signal amount, and sensitivity are greatly affected, which may lead to degraded image quality at the time of a bright state.
Furthermore, there is also a method of controlling the dark signal through adjustment of an implantation layout around a pixel ground (GND) contact (see JP 2011-210837A, for example). In this method, because P+ ions are implanted at a relatively high concentration in the vicinity of an N-type region of a photodiode, occurrence of white dots or dark electric current may be concerned. In addition, because the high concentrated P+ region exists below element isolation, a depletion layer of the photodiode may be limited in a transverse direction, which may raise a concern of deterioration of saturation or sensitivity characteristics. Moreover, when donor impurities are doped at a relatively high concentration as countermeasures of such deterioration, the white points or dark electric current may become more problematic.
In addition, there is a method of reducing a degree of shading in the effective pixel by greatly enlarging a pixel extension region outside the effective pixel region in order to suppress an effect of the dark signal shading, which is typified by non-uniformity of dark electric currents in frame regions. In this method, a size of a chip may be increased by an amount of the pixel extension region, which may directly lead to decreased production yield and increased production costs.
Moreover, there is a method of correcting the OPB level difference and the dark signal shading by utilizing a pixel signal process. In this method, additional memories are necessary for the signal process, which may raise a concern of degraded image quality due to noises associated with the process.